Power converters are used in aircraft electrical power systems as well as in power systems for other apparatus. The electrical power systems on current commercial aircraft are primarily provided by 400 Hz, three-phase 115V or 230V AC power sources. The power system may include one or more alternative low voltage DC power sources, such as a fuel cell stack or a battery, which provides input power to a pulse width modulated (PWM) power conversion system. Multiphase voltage outputs, such as three-phase voltages, maybe provided to an aircraft electric power distribution system, which provides the electrical power to a downstream distribution system. The downstream distribution system may have loads of various types, including, but not limited to, three-phase, single-phase, or another conversion system with DC loads, etc.
Many power converters, however, are not fully optimized for aircraft applications. Such power converters may be large and heavy, increasing the weight of the aircraft and limiting the volume available to other aircraft components. To address this issue, power converters may include paralleled or interleaved inverters. By using paralleled or interleaved inverters, the conversion systems may achieve higher power while concurrently using lower rating devices, thus also achieving higher efficiency, higher power density (measured in kW/kg), and weight and volume savings. Additionally, interleaved converters improve the harmonic reduction compared with non-interleaved converters. However, such converter systems may generate circulating current, which may degrade the performance or cause malfunctions, even to the point of damaging the user equipment connected to the power bus.
In power converters employing paralleled or interleaved inverters, the inverter outputs may be connected to inductive components to limit the circulating current. However, the inductive components often do not work well in low frequency circulating current. The low frequency circulating currents may cause saturation of the cores of the inductive components. Saturation of the cores may reduce the performance of the power converter as well as disable the conversion system.
Also in designing the power converter, large magnetizing inductances may be desired to reduce core loss and better limit high frequency circulating currents. However, this may require advanced and accurate knowledge of system parameters, which makes the design process complicated and time-consuming. For example, the complexity of control system design may be caused by a reduced margin on the flux of a given magnetic core when a large magnetizing inductance is desired.
Therefore, there are at least two problems associated with power conversion systems. They may experience reduced performance when used with high transient loads. Also, the design process may complicated and time-consuming.